1. Field of the Invention
This invention relates to an apparatus and method for generating call information data for calls of long duration from a telephone network, particularly, though not exclusively, to an apparatus and method for generating call information data for calls of long duration from a telephone network having out-of-band signalling.
2. Brief Description of Related Developments
In modern switched telecommunications systems (in particular, modern PSTNs) it has become common practice to provide two related but separate network infrastructures: a bearer or transmission network for carrying end-user voice and data traffic, and a signalling network for controlling the setup and release of bearer channels through the bearer network in accordance with control signals transferred through the signalling network (sometimes known as out-of-band signalling). In practice, such signalling networks comprise high-speed computers interconnected by signalling links; computer programs control the computers to provide a set of operational and signalling functions in accordance with a standardised protocol. One example of such a signalling protocol is the Signalling System No. 7 (SS7), whether as specified by the CCITT, ANSI, ETSI (for GSM), Bellcore or similar body, such as a network being herein referred to as an SS7 network. SS7 networks are extensively deployed for control of telephone and other data transmission networks and basically comprise various types of signalling points, namely, Signalling End Points (SEPs), for example an end office or local exchange, and Signalling Transfer Points (STPs) interconnected by signalling links, the SEPs being associated for example with respective Signalling Switching Points (SSPs) of the transmission network, and with Signalling Control Points (SCPs).
In SS7 networks, signalling information is passed over the signalling links. In particular, the signalling information is used by a CDR Builder to generate a Call Detail Record (CDR) which can later be analysed. For example, the CDRs can be analysed by reference to a particular customer of a telecommunications company (telco) operating the SS7 system, or certain types of data can be mined from Call Detail Records maintained by telcos in databases, including, for example, billing databases.
The CDRs may be generated by an apparatus, such as the product developed by Agilent Technologies and known as “acceSS7”. This apparatus consists of a CDR Builder, a CDR Agent and a Data Management Component (DMC). The CDR Builder monitors the signaling channels of the SS7 network and generates the CDRs, which are then passed via the CDR Agent to the DMC, where they are processed and correlated to provide a database of the records that can be viewed by interested parties, for example, telcos. In some systems, some processing of the data (Interconnect Analysis) can take place prior to the CDRs being stored in the DMC, for example, the CDRs can be analysed to categorise the calls in various ways so that database has enhanced information regarding the calls. An interface is provided to the databases so that the telcos can carry out various processing and analysis functions, for example, checking billing, checking that data is transferred correctly, checking for quality of service, etc.
One function that the telcos often carry out is to correlate and check groupings and totals CDRs (as may be provided by the Interconnect Analysis) with their own records of calls generated, for example, by switches in the telecommunications network. However such processing, analysis or comparison with other types of data record, can be complicated by differences in the methods of generating the different call records. In particular, problems can arise when trying to correlate call records for long duration calls that last for more than 24 hours (often lasting several days). Such long duration calls are becoming more and more frequent, especially in territories where some types of calls are very cheaply priced, or free, or more especially, where there is a flat rate charge per call, in which case it is cheaper to stay connected, for example for an internet or other data connection, than it is to disconnect and reconnect. One problem that can occur with such long duration calls is that call records that telcos may have will provide data for all calls over a particular day, even if the call has not been completed, whereas the acceSS7 apparatus only generates a CDR when a call is actually completed. Therefore, if a call lasts several days, the CDR will be generated at the completion of the call and cannot easily be correlated with the call records relating to that call generated daily and used by the telco to compare records and check billing. The main problem is that a telco has no easy way to verify that a usage figure given to it by another operator is correct. The need is to ensure that the other operator is using the amount of time that they say they are. At the moment it is hard to verify this due to the reasons mentioned above.